I threw my engine and transmission (separately) onto an engine stand and hit it with Simple Green and a nylon brush, then rinsed with a low flow setting on the garden hose. As long as you're not drenching sensors in chemicals or blasting them with water, everything should be fine. I taped over the intake and exhaust ports with masking tape and the tape managed to hold up, if that tells you how much liquid I didn't have to use to get stuff clean.